This disclosure relates generally to an integrated antenna unit and more specifically to an antenna unit with an integrated and replaceable remote radio unit.
Conventional antenna systems include an antenna mounted on a supporting tower and a base station at ground level (or sometimes on a rooftop). The base station and the antenna are connected together using coaxial cables, often 100 ft. or more in length. Because of advances in technology, the radio equipment in the base station has become smaller and consumes less power. Therefore, in order to reduce signal loss caused by the coaxial cables (that can be as much as 3 dB, or 50% of the signal power), some conventional antenna systems include a remote radio unit that is mounted on the supporting tower.
A remote radio unit may be fed using an optical fiber line, which conveys the digital input/output signals. The remote radio unit may include modulation circuits that impress the digital information on a radio frequency carrier signal, amplifiers that increase the power of radio frequency signal to the desired level for transmission, etc. In the receive direction, the remote radio unit may include circuits to amplify the incoming signal, demodulate the signal to extract the digital data it was carrying, and circuits to couple the demodulated signal to the optical fiber line.
FIG. 1 is a block diagram illustrating a prior art antenna system, including an extra-wideband antenna 11, a transmission circuit 10, and at least one remote radio unit 2 connected to the antenna by jumper cables 101 and 102. The jumper cables may be coaxial cables with threaded ring connectors. This example is typical of prior art installations in which the antenna 11 receives two radio mobile radio services. One mobile radio service is provided by radio equipment located remotely from the antenna unit via a coaxial cable 100 and a second mobile radio service is provided to the remote radio unit 2 by ground-level equipment via a signal/power line 103, which may include optical fiber lines. The antenna 11 is capable of transmitting/receiving radio signals over a wide band while the remote radio unit 2 operates over specific narrower frequency bands.
In response to changes in spectrum management or radio access technology, the prior art antenna system illustrated in FIG. 1 allows an operator to remove and replace the remote radio unit 2. The prior art antenna system, however, has a number of drawbacks. Connecting the remote radio unit 2 to the antenna 11 using the jumper cables 101 and 102 increases installation time and introduces losses to the system.
Other prior art antenna systems integrate the remote radio unit 2 within the antenna 11. An integrated remote radio unit 2 and antenna 11 is aesthetically pleasing and eliminates the need for jumper cables. In order to respond to changes in spectrum management or radio access technology, however, an integrated remote radio unit 2 and antenna 11 must be completely replaced at considerable expense.
Accordingly, there is a need for an integrated antenna unit including an extra-wideband antenna and an integrated, field replaceable remote radio unit.